1. Field of the Invention
The present invention relates to a fuel cell vehicle and a method of controlling a fuel cell and a storage battery provided in the fuel cell vehicle.
2. Description of the Related Art
A typical polymer electrolyte fuel cell includes an electrolyte membrane (electrolyte)-electrode assembly in which an electrolyte membrane formed by a polymer ion exchange membrane (a cation exchange membrane) is held between an anode electrode and a cathode electrode, and separators between which the assembly is held. Fuel cells of this type are in general provided as fuel cell stacks each obtained by stacking a specific number of cells each including an electrolyte membrane-electrode assembly and separators.
In such a fuel cell stack, a fuel gas, for example, a hydrogen-containing gas, supplied to the anode electrode is hydrogen-ionized by an electrode catalyst, passes through the electrolyte membrane moistened to an appropriate level, and moves to the cathode electrode. Electrons produced in this movement are taken by an external circuit and are used as direct-current electric energy. The cathode electrode is supplied with an oxidant gas, for example, an oxygen-containing gas such as air. Therefore, the hydrogen ions, the electrons, and the oxygen react to each other at the cathode electrode, whereby water is produced.
Japanese Unexamined Patent Application Publication No. 2001-325976 ([0064] to [0067] and FIG. 6) proposes a technique relating to a fuel cell vehicle that runs on a fuel cell, such as the one described above, and a storage battery both functioning as drive sources with a motor functioning as a power source.
In the technique proposed by Japanese Unexamined Patent Application Publication No. 2001-325976, the output of the fuel cell is made to follow the degree of accelerator opening (an output required by a load) in such a manner as to become higher as the remaining capacity in the storage battery becomes smaller.
In such a technique, however, in which the output of the fuel cell is controlled to follow the output required by the load, the fuel cell may be overloaded and the durability of the fuel cell may be reduced because of, for example, a high possibility of damage on the electrolyte membrane. Consequently, the durability of the fuel cell vehicle may be reduced.